The proper functioning of the body's biological processes depends on vitamins: avoiding deficiencies is therefore essential for promoting wellbeing. Vitamins are organic compounds found in abundance in vegetables, fruit, pulses, but also in egg yolk and liver. A natural, varied, wholefood diet rich in plant foods supplies the body with all the vitamins and antioxidants it needs; however, it is important to handle them carefully, as vitamins are delicate. Heat, cold and light can easily destroy them.

To limit nutrient loss, a few simple rules are all that is needed: buy fresh fruit and vegetables, rinse them under running water and avoid soaking; cut only after washing and eat straight away. When cooking is necessary, it should generally be brief. Vegetables should not be cooked long before eating, but right at the time of consumption.

The World Health Organisation recommends eating 5 portions of fruit and vegetables a day in order to benefit from their protective effect on health. According to a large study conducted by the Department of Nutrition and Epidemiology at Harvard University and published in the British Medical Journal, this recommendation appears to be truly the ideal one for ensuring the body receives all the benefits of plant foods. The research shows that for each portion of fruit or vegetables eaten, the probability of death from all causes decreases by 5 per cent, and the risk of cardiovascular diseases such as heart attack and stroke decreases by 4 per cent. The credit, according to the researchers, goes to the antioxidants found in plant foods — such as vitamin C, carotenoids and flavonoids — which prevent the oxidation of cholesterol and increase the synthesis of substances that inhibit platelet aggregation, thereby reducing the risk of atherosclerotic plaque formation. "Moreover," specifies Frank Hu, the study's author, "fruit and vegetables appear to be able to reduce vascular tone and, consequently, blood pressure; furthermore, fruit and vegetables are rich in minerals such as magnesium and potassium, which are associated with a reduction in mortality."

What does 5 portions of fruit and vegetables weigh? At least 400 grams in total per day, say experts; in the case of fruit, allow 100 grams per piece (three to four pieces in the case of plums or apricots); for vegetables it is better to distinguish between raw and cooked consumption: 100 grams of vegetables when eaten raw and 250 grams when cooked, because water and heat reduce their nutritional properties.

A glass of any fresh fruit and vegetable juice counts as 1 portion. Dark green vegetables have a high free-radical-fighting power; pungent, sulphurous ones are the most effective (even white ones, such as garlic and onion). Colourful vegetables are also excellent: red and yellow peppers, red cabbage, dark orange carrots, pumpkin, ripe tomatoes, beetroot. Fruit should be, at peak ripeness, the most acidic or colourful (yellow-red-bluish-black): oranges, apricots, grapefruit, mandarins, blackberries, blueberries, black grapes, black plums, strawberries, cherries, peaches, pineapple, kiwi, persimmons. Bear in mind that the skin contains the majority of antioxidants. Eating a little citrus zest is also advisable, but only if organically grown.